Offshore platform for underwater facilities



May 21, 1968 D. E. COSTELLO 3,

OFFSHORE PLATFORM FOR UNDERWATER FACILITIES Filed 001:. 28,, 1966 ELLO INVENTOR.

DANIEL E. 6057' United States Patent 3,383,870 OFFSHORE PLATFORM FOR UNDERWATER FACILITIES Daniel E. Costello, Elmhurst, N.Y., assignor to The Lummus Company, New York, N.Y., a corporation of Delaware Filed Oct. 28, 1966, Ser. No. 590,347 7 Claims. (Cl. 61-48) ABSTRACT OF THE DISCLOSURE An olfshore platform for servicing an underwater facility is provided, incorporating a floating barge. The barge supports fluid and/ or slurry handling or processing equipment and is moored to the structure by means of fenders which permit motion of the barge relative the structure. Flexible fluid connections are provided bet-ween the barge and the facility.

This disclosure relates to underwater facilities such as pipelines. The invention resides in an offshore service platform which incorporates a floating barge.

It is often expedient to locate processing or handling equipment on offshore platforms. These platforms are usually supported on piles. Relatively stationary risers connect the equipment with originating, gathering or distributing systems situated on the bottom. However, pile supported ofishore platforms involve the following problems:

The number and length of piles required, particularly in deep water, are considerable with attendant high cost.

Building the platform over open water entails difl'lcult and costly construction.

Installing equipment on the platform over Water gives rise to inconvenience, delay and expense.

Salvage of equipment mounted on the platform is burdened by charges for marine lifting equipment and the like.

A pile supported platform in deep Water has mechanical properties in common with an inverted pendulum. Such a platform is susceptible to damage from earthquakes as well as from subsidence of the bottom.

Natural vibration frequencies of pile supported platforms tend to fall within the working ranges of turbine and engine driven equipment.

Applicant has developed an offshore platform which avoids these problems in a novel and facile way. Piles are employed to anchor a fixed mooring structure as well as to support risers which are connected to the underwater pipeline. A barge is fitted out to support fluid and/or slurry handling or processing equipment and is moored to the structure by means of fenders which permit some relative motion between the barge and the stiucture. For convenience of presentation fluids will here be construed to include slurries: Handling equipment will be construed to include processing equipment. Fluid connections for low pressure services are made via flexible conduits. For high pressure services, pipes with swivel joints are used to provide fluid connections.

Basically this teaching offers a reduction in the number of piles. In comparison with a conventional pile supported platform, only a minor portion of the piles are here needed, say from to 30 percent. A simple cap structure is all that has to be assembled over water. The barge can be built and equipped on or alongside shore where it is close to labor, supplies, warehouses, electricity and other facilities thereby saving time and expense. Salvage of the barge and equipment is also facilitated. Possibilities of damage from earthquakes and subsidence are practically nil. Also, design modification necessary to 3,383,870 Patented May 21, 1968 ICC avoid damaging vibration buildup due to resonance with running equipment is easily accomplished for barges. These and other features will appear more fully from the accompanying drawings wherein:

FIGURE I is a plan view of an offshore platform according to this invention.

FIGURE II is a fragmented elevation view taken along line IIII of FIGURE I.

FIGURE III is an enlarged detail showing a mooring fender and a flexible conduit.

FIGURE IV is an enlarged detail showing a swiveljointed pipe arrangement suitable for accommodating motion between the barge and the fixed structure.

As seen in the drawings, barge 1 serves to support fluid-handling equipment 2 thereon. Barge 1 has bulkheads 3 which define compartments 4 so that leaks will be locally contained. A pumping system (not shown) controls overall and differential ballasting in and among compartments 4. Although it will be towed to its site, barge 1 is intended for stationary duty, so it can be designed suitably square to minimize responses to wave action.

Barge 1 must be securely moored. Toward this objective fixed structure 6 is formed as a cap on piles 7 and is tailored to the requirements of barge 1 as well as to the location of risers such as riser 8 from pipeline 9. Piles 7 are driven on appropriate batters to increase their horizontal thrust resisting abilities. The pile cap is constructed of heavily reinforced concrete so that it enables piles 7 to act as a group. It should be understood that in some instances horizontal thrusts can be accommodated by driving vertical piles through a rigid jacket located at the bottom.

This mooring arrangement allows some motion of barge 1 relative fixed structure 6, but shock or impact loads have to be minimized. Steel fenders 11 are provided between barge 1 and fixed structure 6. Universal joints 12 are furnished at both ends of fenders 11. Fenders 11 transmit horizontal forces from barge 1 to fixed structure 6 so that the barge remains substantially in position under wave, wind and current forces. Fenders 11 permit the barge to rise and fall with tidal action as well as to roll, pitch and yaw under the effects of external forces. Slack is eliminated as much as possible to avoid impact loading. Conventional rubber bumpers are provided against the possibility that the fender system might fail.

At;the core of this disclosure is the handling of relative motion between floating barge 1 and fixed structure 6. Riser 8 is supported from and is integral with fixed structure 6; however, barge 1 is subject to movement. For small diameter and for low pressure lines, riser 8 may be connected to fluid-handling equipment 2 by means of flexible conduit 14 as shown in FIGURE II. But services with any appreciable sizes or pressure generally require swivel joint 16 and pipe 17 assemblies such as the one shown in FIGURES III and IV. This assembly allows for rotation about X-X, YY and ZZ axes simultaneously. Swivel joints 16 are fitted with ball bearings 18. Periodic maintenance of these swivel joints is essential, and is facilitated by manifolding and sparing the conduits so that any one may be taken out of service for maintenance without having to interrupt operations.

embodiment without departing from the spirit of invention set forth in the claims.

What is claimed is:

1. An offshore platform for service with an underwater facility comprising a relatively fixed structure having a plan view substantially L-shaped to define legs,

a barge moored to the structure between the legs thereof, fenders mooring the barge to the structure, the fenders being connected to both the barge and structure by means of universal joints,

the barge being connected to each of said legs by a plurality of fenders,

at least one riser supported from the structure and connected in flow communication with the facility, and

a conduit connecting the riser in flow communication with the barge,

the conduit including means for accommodating motion of the barge relative the structure.

2. The platform of claim 1 with the barge having fluid-handling equipment mounted therein,

the conduit connecting the riser in fiow communication with the fluid-handling equipment.

3. The platform of claim 2 with piles supporting the fixed structure.

4. The platform of claim 3 with means for restraining the structure from horizontal motion.

5. The platform of claim 4 with the barge defining a plurality of cells,

means for regulating the buoyant effect of at least two of these cells.

6. The platform of claim 4 with the conduit made of flexible hose.

7. The platform of claim 4 with the conduit made of pipe, the conduit provided with a plurality of swivel joint assemblies.

References Cited UNITED STATES PATENTS 2,768,600 10/1956 Harris 61-48 X 2,920,597 1/1960 Dick 114-230 2,945,465 7/1960 Barton 61-48 X 3,050,092 8/1962 Palcanis 141-387 3,086,367 4/1963 Foster 61-46 3,120,106 2/1964 Foster 61-465 3,245,438 4/1966 McCammon 141-387 JACOB SHAPIRO, Primary Examiner. 

